Generally, basic processing steps for processing silver halide color photographic sensitive materials are the color development step and the desilvering step. More specifically, in the color development step, silver halide in the exposed silver halide color photographic material is reduced by a color developing agent to form silver and the oxidized color developing agent reacts with couplers to form dye images. Thereafter, the color sensitive material is treated in the desilvering step, where silver formed in the prior step is oxidized by the action of an oxidizing agent (which is generally called a bleaching agent). The oxidized silver is then removed from the photographic material by dissolution with a complexing agent for silver ions called a fixing agent. Thus, only dye images can be formed on the photographic material. The practical development processing includes supplementary steps for maintaining the photographic and physical quality of images or for improving preservation stability of images to an extent beyond that possible with the above-described two basic steps of color development and desilvering. For example, it is possible to use a hardening bath to prevent excessive softening of the sensitive layer during processing, a stopping bath for effectively stopping the development reaction, an image stabilizing bath for stabilizing the images, or a defilming bath for removing a backing layer of the base, etc.
There are two variations of the above-described desilvering step. In accordance with one, the processing is carried out in one stage using a bleach-fixing bath containing a bleaching agent and a fixing agent. In accordance with the other, the processing is carried out in two stages of bleaching and fixing using different baths.
Examples of useful bleaching agents for the bleaching solution include ferricyanides, potassium bichromate, ferric ion complex salts and persulfates. A bleaching solution containing ferricyanides has been found to have a particularly excellent bleaching function. However, ferricyan ions and ferrocyan ions exhausted by overflowing during the processing or placement in the washing water after bleaching are subjected to photochemical oxidation and thus form cyan compounds which have high toxicity and cause injury. Accordingly, it is desired to develop a bleaching agent which takes the place of ferricyanides.
Ferric ion complex salts are sometimes used as bleaching agents in a bleach-fixing solution for color printing paper. (German Pat. Nos. 866,605 and 966,410, and British Pat. Nos. 746,567, 933,008 and 1,014,396.) However, since the bleaching solution or the bleach-fixing solution containing ferric ion complex salts has a poor oxidation ability, a long period of time is required for processing when using color sensitive photographic materials which include silver iodobromide having a high concentration of silver halide.
In any case, bleach processing with the use of metal ions such as those of ferricyanides or ferric ion complex salts cause pollution of water liquor. Accordingly, processes which do not use metal ions, for example, persulfate bleaching processes, are more suitable. However, the persulfate bleaching bath is not desirable because it has weaker bleaching ability than ferric ion complex salts and the bleaching requires a very long period of time. Therefore, when using color sensitive materials with photographic sensitivity which contains a large amount of silver halide, it would be desirable to develop new techniques for promoting the persulfate bleaching.
Examples of processes for promoting bleaching with persulfates include processes which involve adding amino compounds described in, for example, U.S. Pat. Nos. 3,772,020 and 3,893,858 and Research Disclosure, No. 15704, etc., to treating solutions (a bleaching bath, a bleach-fixing bath or a previous bath thereof).
However, these processes also require a fairly long period of time to sufficiently carry out bleaching. Further, since many of the above-described amino compounds give out a bad smell, it is not desirable to add them to treating solutions.
Further, according to these processes, it is difficult to sufficiently bleach color sensitive materials having a high silver content which have colloidal silver layers such as a yellow filter layer or an antihalation layer, etc., while preventing an increase in fogs caused by said colloidal silver during preservation.